Problem: Constraints

* H is an integer between 2 and 50 (inclusive).
* W is an integer between 2 and 50 (inclusive).
* s_{i, j} is `.` or `#` (1 \leq i \leq H, 1 \leq j \leq W).
* s_{1, 1} and s_{H, W} are `.`.

Input

Input is given from Standard Input in the following format:


H W
s_{1, 1}s_{1, 2}s_{1, 3} ... s_{1, W}
s_{2, 1}s_{2, 2}s_{2, 3} ... s_{2, W}
:   :
s_{H, 1}s_{H, 2}s_{H, 3} ... s_{H, W}


Output

Print the maximum possible score that Snuke can achieve, or print -1 if the game cannot be completed.

Examples

Input

3 3
..#
#..
...


Output

2


Input

3 3
..#
..
...


Output

2


Input

10 37
.....................................
...#...####...####..###...###...###..
..#.#..#...#.##....#...#.#...#.#...#.
..#.#..#...#.#.....#...#.#...#.#...#.
.#...#.#..##.#.....#...#.#.###.#.###.
.#####.####..#.....#...#..##....##...
.#...#.#...#.#.....#...#.#...#.#...#.
.#...#.#...#.##....#...#.#...#.#...#.
.#...#.####...####..###...###...###..
.....................................


Output

209

Solution (in CPP):

Solution:
#include <iostream>
#include <algorithm>
#include<cmath>
#include<cstring>
#include<cstdio>
#include<cstdlib>
#include<vector>
#include<iomanip>
#include<queue>
#define sqr(x) (x)*(x)
using namespace std;
int dx[5]={0,0,0,-1,1},dy[5]={0,-1,1,0,0};
int n,m,i,j,cnt,dis[55][55];
char mp[55][55];
int main()
{
	cin>>n>>m;
	for (i=1;i<=n;i++)
	{
		for (j=1;j<=m;j++)
		{
			cin>>mp[i][j];
			if (mp[i][j]=='.') cnt++;
		}
	}
	memset(dis,22,sizeof(dis));
	dis[1][1]=1;
	queue<int> qx,qy;
	qx.push(1);
	qy.push(1);
	while (!qx.empty())
	{
		int x=qx.front(),y=qy.front();
		qx.pop();qy.pop();
		for (i=1;i<=4;i++)
		{
			int xx=x+dx[i],yy=y+dy[i];
			if (xx<1||yy<1||xx>n||yy>m) continue; 
			if (mp[xx][yy]=='#') continue;
			if (dis[xx][yy]>dis[x][y]+1)
			{
				dis[xx][yy]=dis[x][y]+1;
				qx.push(xx);
				qy.push(yy);
			}
		}
	}
	if (dis[n][m]>n*m)
	{
		cout<<-1;
		return 0;
	}
	cout<<cnt-dis[n][m];
	return 0;
}